Plasma cathodes for large volume, high-pressure glow discharges

Summary form only given. In high pressure glow discharges is motivated by applications such as instantly activated reflectors and absorber for electromagnetic radiation, plasma processing, gas lasers, and the remediation of gaseous pollution. One of the main obstacles for DC operation of high-pressure glow discharges is the glow-to-arc transition, an instability that originates in the high field region of the discharge: the cathode fall. Away to suppress this instability is the use of a plasma cathode consisting of microhollow cathode discharges (MHCD). In our experiment a microhollow cathode discharge with a 100 /spl mu/m diameter cathode hole and identical anode hole was used to provide electrons for a large volume main discharge, sustained between the hollow anode of the MHCD and a third electrode. The distance of this electrode from the MHCD anode was varied between 2.5 mm to 9.5 mm, a value large compared to the 200 /spl mu/m anode-cathode gap of the MHCD. Current and voltage characteristics, and the visual appearance of the main discharge and MHCD were studied in argon and air at pressures up to several hundred Torr. Using the micro plasma cathode as electron source to support the main discharge we are able to get a stable dc operation in argon up to pressures of more than 400 Torr without reaching the threshold for glow-to-arc transition.